Re: [virtio-dev] [PATCH 4/4] virtio-net: add linkspeed and duplex settings to virtio-net

[Yan Vugenfirer]

> On 6 Mar 2018, at 20:13, Michael S. Tsirkin  wrote:
> 
> On Tue, Mar 06, 2018 at 01:02:06PM -0500, Jason Baron wrote:
>> 
>> 
>> On 03/04/2018 08:05 AM, Yan Vugenfirer wrote:
>>> 
>>> 
 On 2 Mar 2018, at 22:19, Michael S. Tsirkin > wrote:
 
 On Fri, Mar 02, 2018 at 03:14:01PM +0800, Jason Wang wrote:
> 
> 
> On 2018年03月02日 11:46, Jason Baron wrote:
>> Although linkspeed and duplex can be set in a linux guest via
>> 'ethtool -s',
>> this requires custom ethtool commands for virtio-net by default.
>> 
>> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
>> the hypervisor to export a linkspeed and duplex setting. The user can
>> subsequently overwrite it later if desired via: 'ethtool -s'.
>> 
>> Linkspeed and duplex settings can be set as:
>> '-device virtio-net,speed=1,duplex=full'
> 
> I was thinking whether or not it's better to decide the duplex by the
> type
> of backends.
> 
> E.g userspace and vhost-kernel implement a in fact half duplex. But dpdk
> implement a full duplex.
> 
> Thanks
 
 OTOH it's a priority for some people to be able to support migration
 between different backend types. Breaking that won't be nice.
>>> 
>>> I think that in this case we need a way to update the settings of link
>>> speed and link duplex (maybe add QMP command). Migration between
>>> different backend types should cause link down\link up events. And this
>>> is a time for a driver to re-read the settings and update the OS.
>>> 
>>> Best regards,
>>> Yan.
>>> 
>> 
>> So the virtio_net driver in linux will re-read these settings on link up
>> events. So I could add a qmp command to set these (in addition to the
>> command-line) interface, if desired. Is there a consensus that we need
>> to add a qmp command here? Or can that be treated as a future item, if
>> somebody wants it?
>> 
>> Thanks,
>> 
>> -Jason
> 
> We already have ability to take link down and up.
> I'd say it's a future item.
I agree.

Yan.
> 
> -- 
> MST


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Re: [virtio-dev] [PATCH 4/4] virtio-net: add linkspeed and duplex settings to virtio-net

[Michael S. Tsirkin]

On Tue, Mar 06, 2018 at 01:02:06PM -0500, Jason Baron wrote:
> 
> 
> On 03/04/2018 08:05 AM, Yan Vugenfirer wrote:
> > 
> > 
> >> On 2 Mar 2018, at 22:19, Michael S. Tsirkin  >> > wrote:
> >>
> >> On Fri, Mar 02, 2018 at 03:14:01PM +0800, Jason Wang wrote:
> >>>
> >>>
> >>> On 2018年03月02日 11:46, Jason Baron wrote:
>  Although linkspeed and duplex can be set in a linux guest via
>  'ethtool -s',
>  this requires custom ethtool commands for virtio-net by default.
> 
>  Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
>  the hypervisor to export a linkspeed and duplex setting. The user can
>  subsequently overwrite it later if desired via: 'ethtool -s'.
> 
>  Linkspeed and duplex settings can be set as:
>  '-device virtio-net,speed=1,duplex=full'
> >>>
> >>> I was thinking whether or not it's better to decide the duplex by the
> >>> type
> >>> of backends.
> >>>
> >>> E.g userspace and vhost-kernel implement a in fact half duplex. But dpdk
> >>> implement a full duplex.
> >>>
> >>> Thanks
> >>
> >> OTOH it's a priority for some people to be able to support migration
> >> between different backend types. Breaking that won't be nice.
> > 
> > I think that in this case we need a way to update the settings of link
> > speed and link duplex (maybe add QMP command). Migration between
> > different backend types should cause link down\link up events. And this
> > is a time for a driver to re-read the settings and update the OS.
> > 
> > Best regards,
> > Yan.
> > 
> 
> So the virtio_net driver in linux will re-read these settings on link up
> events. So I could add a qmp command to set these (in addition to the
> command-line) interface, if desired. Is there a consensus that we need
> to add a qmp command here? Or can that be treated as a future item, if
> somebody wants it?
> 
> Thanks,
> 
> -Jason

We already have ability to take link down and up.
I'd say it's a future item.

-- 
MST

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Re: [virtio-dev] [PATCH 4/4] virtio-net: add linkspeed and duplex settings to virtio-net

[Jason Baron]

On 03/04/2018 08:05 AM, Yan Vugenfirer wrote:
> 
> 
>> On 2 Mar 2018, at 22:19, Michael S. Tsirkin > > wrote:
>>
>> On Fri, Mar 02, 2018 at 03:14:01PM +0800, Jason Wang wrote:
>>>
>>>
>>> On 2018年03月02日 11:46, Jason Baron wrote:
 Although linkspeed and duplex can be set in a linux guest via
 'ethtool -s',
 this requires custom ethtool commands for virtio-net by default.

 Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
 the hypervisor to export a linkspeed and duplex setting. The user can
 subsequently overwrite it later if desired via: 'ethtool -s'.

 Linkspeed and duplex settings can be set as:
 '-device virtio-net,speed=1,duplex=full'
>>>
>>> I was thinking whether or not it's better to decide the duplex by the
>>> type
>>> of backends.
>>>
>>> E.g userspace and vhost-kernel implement a in fact half duplex. But dpdk
>>> implement a full duplex.
>>>
>>> Thanks
>>
>> OTOH it's a priority for some people to be able to support migration
>> between different backend types. Breaking that won't be nice.
> 
> I think that in this case we need a way to update the settings of link
> speed and link duplex (maybe add QMP command). Migration between
> different backend types should cause link down\link up events. And this
> is a time for a driver to re-read the settings and update the OS.
> 
> Best regards,
> Yan.
> 

So the virtio_net driver in linux will re-read these settings on link up
events. So I could add a qmp command to set these (in addition to the
command-line) interface, if desired. Is there a consensus that we need
to add a qmp command here? Or can that be treated as a future item, if
somebody wants it?

Thanks,

-Jason

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Re: [virtio-dev] [PATCH 4/4] virtio-net: add linkspeed and duplex settings to virtio-net

[Yan Vugenfirer]

> On 2 Mar 2018, at 22:19, Michael S. Tsirkin  wrote:
> 
> On Fri, Mar 02, 2018 at 03:14:01PM +0800, Jason Wang wrote:
>> 
>> 
>> On 2018年03月02日 11:46, Jason Baron wrote:
>>> Although linkspeed and duplex can be set in a linux guest via 'ethtool -s',
>>> this requires custom ethtool commands for virtio-net by default.
>>> 
>>> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
>>> the hypervisor to export a linkspeed and duplex setting. The user can
>>> subsequently overwrite it later if desired via: 'ethtool -s'.
>>> 
>>> Linkspeed and duplex settings can be set as:
>>> '-device virtio-net,speed=1,duplex=full'
>> 
>> I was thinking whether or not it's better to decide the duplex by the type
>> of backends.
>> 
>> E.g userspace and vhost-kernel implement a in fact half duplex. But dpdk
>> implement a full duplex.
>> 
>> Thanks
> 
> OTOH it's a priority for some people to be able to support migration
> between different backend types. Breaking that won't be nice.

I think that in this case we need a way to update the settings of link speed 
and link duplex (maybe add QMP command). Migration between different backend 
types should cause link down\link up events. And this is a time for a driver to 
re-read the settings and update the OS.

Best regards,
Yan.

> 
>>> 
>>> where speed is [0...INT_MAX], and duplex is ["half"|"full"].
>>> 
>>> Signed-off-by: Jason Baron
>>> Cc: "Michael S. Tsirkin"
>>> Cc: Jason Wang
>>> Cc:virtio-dev@lists.oasis-open.org
>>> ---
> 
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